crack·pot 
/ˈkrækˌpɑ:t/ noun
plural crack·pots /ˈkrækˌpɑ:t/ noun [count] informal : a person who is crazy or very strange
▪ Some crackpot in a clown suit is out there directing traffic.
▪ Some crackpot in a clown suit is out there directing traffic.
— crackpot adjective always used before a noun
▪ a crackpot philosophy/idea
▪ a crackpot philosophy/idea
